Simultaneous improvement of strength and ductility in NiAl–Cr(Mo)–Hf near eutectic alloy by small amount of Ti alloying addition

Effects of Ti alloying addition on the microstructure and room temperature compression deformation behavior of a NiAl–Cr(Mo)–Hf near eutectic alloy were investigated by SEM, TEM, EDX and compression test. The results showed that compared with base alloy, the compressive fracture strain and 0.2% yield strength of the Ti-containing alloy were enhanced simultaneously. Disordered (Ti,Hf) solid solution phase together with the blocky Heusler phase Ni2Al(Ti,Hf) precipitation presented at eutectic cell boundaries is responsible for the enhancement in ductility due to the better deformation ability of (Ti,Hf) solid solution phase. The improvement in strength depends mainly on the solid solution strengthening in NiAl matrix by large amount of Ti due to its larger solid solubility relative to Hf in NiAl.